Non-clinical immunological comparison of a Next-Generation 24-valent pneumococcal conjugate vaccine (VAX-24) using site-specific carrier protein conjugation to the current standard of care (PCV13 and PPV23)

Non-Native Amino Acid Click Chemistry-Based Technology for Site-Specific Polysaccharide Conjugation to a Bacterial Protein Serving as Both Carrier and Vaccine Antigen

“… 44 − 46 Typical yields of protein expression and purification with this system have been reported. 47 We previously used Xpress + CFPS to generate an SLO C-terminal truncation variant SLO(ΔC101) ( Figure 1 A) that elicited SLO neutralizing antibodies and contributed to protection against GAS challenge in vivo . 22 To prepare SLO(ΔC101) for use as a carrier protein, we analyzed its sequence and selected several solvent-exposed lysine and arginine residues as sites to incorporate the non-native amino acid (nnAA) p -azidomethyl phenylalanine (pAMF).…”

“…Typical yields of glycoconjugation reaction and purification with this method have been reported in our work with a 24-valent pneumococcal capsule conjugate vaccine. 47 Each carrier protein was mixed with DBCO-GAC PR in a 1:1 mass ratio (0.5 mg/mL each) for 4 h at room temperature with constant stirring. Thereafter, the reactions were harvested, and the conjugated polysaccharides were dialyzed against the buffer to remove excess free GAC PR .…”

“…Antigen-specific serum IgG titers specific for SLO were measured by ELISA, as previously described. 22 Briefly, NUNC ELISA plates (NUNC Maxisorp) were coated with in-house-purified SLO, as reported elsewhere, 22 or with a conjugate vaccine using eCRM 47 as the carrier protein at 1 and 5 μg/mL, respectively, in PBS pH 7.4 and incubated overnight at 4 °C. The next day, the plates were washed 3× with standard buffer (Cat # AQUAMAX2000, Molecular Devices) and blocked with blocking buffer (Cat # 37516, Thermo Fisher) for 1 h at room temperature.…”

Glycan Array Evaluation of Synthetic Epitopes between the Capsular Polysaccharides from Streptococcus pneumoniae 19F and 19A

“…One way to overcome the limitations of licensed vaccines is to increase the valency, i.e., the number of vaccine serotypes in the PCV formulations. Fifteen- and twenty-valent vaccine candidates (20vPnC-Pfizer and V114-Merck) are under examination for marketing or license authorizations. , They demonstrated safety and immunogenicity profiles comparable to those of the licensed 13-valent vaccine (PCV13-Pfizer). − In addition, two 24-valent formulations, one of which exploits a new site-specific conjugation technology, are under preclinical evaluation. , However, due to the global variation in serotype prevalence, the search for new vaccine candidates and approaches that elicit broader protection is important considering the efforts involved in vaccine development . Ideal candidates should be protective against a broader range of pneumococcal serotypes, with the possibility of the addition in the vaccine formulation of emerging new clinical isolates.…”

“…12−14 In addition, two 24-valent formulations, one of which exploits a new sitespecific conjugation technology, are under preclinical evaluation. 15,16 However, due to the global variation in serotype prevalence, the search for new vaccine candidates and approaches that elicit broader protection is important considering the efforts involved in vaccine development. 17 Ideal candidates should be protective against a broader range of pneumococcal serotypes, with the possibility of the addition in the vaccine formulation of emerging new clinical isolates.…”